IRVING, Texas -- Two days after their 45-28 loss to the Chicago Bears, Dallas Cowboys executive vice president Stephen Jones was still upset at the defeat that dropped the team out of first place in the NFC East.

"You turn on the tape and guys we count on week in and week out didn't show up," Jones said at the conclusion of an NFL owners meeting at the Four Seasons Resort in Las Colinas. "I don't know what it was, but we didn't get it done and I've got to believe we can do better than that."

With the return of linebacker Sean Lee from a two-game absence because of a hamstring injury and a rested DeMarcus Ware (quadriceps) and Jason Hatcher (stinger) after playing two games in 28 days, the defense was as healthy as it had been since the early part of the season.

Lee hurt his neck and was forced from the game in the second half. He took part in a limited portion of Wednesday's practice and the hope is he can play Sunday against the Green Bay Packers. After the game, Ware acknowledged he has to play better.

"They've all got to be better," Jones said. "Sean Lee has got to be better. Brandon Carr has got to be better. Bruce Carter has got to be better. Jason Hatcher has got to be better. We've all got to be better. We've got to do a better job when we do have injuries of having better players to get up and be there. It's an organizational thing. You just have to do better on the defensive side of the ball. If we want to get to where we want to get to we can't play that type of defense."

Backup quarterback Josh McCown threw four touchdown passes and ran for another as the Bears put up 490 yards on offense, picked up 33 first downs and held the ball for 36 minutes, 44 seconds.

It continued a season-long stretch of poor play. The Cowboys are last in the NFL in yards per game allowed (426.8), last in pass defense (298.5), 28th in run defense (128.4) and 26th in points allowed per game (26.8).

"Obviously you expect better," Jones said. "We have to be better. You can't play defense like that and be last in the league and expect to ultimately get to where we want to get to. Ultimately it's got to improve. We know there's circumstances with injuries -- no excuses -- our defensive line is kind of where it starts. We've been beaten up there but that's part of it and we'll have to keep churning there.

"But I fully expect us to play better these last three games on the defensive side of the ball."

And if it doesn't improve?

"Let's worry about the Green Bay Packers and fix that," Jones said. "We control our destiny. We can go beat the Packers here at home and let's see what happens from there. Obviously we're in control of what we control and if we do what we need to do and should do then good things will happen for this team."